FR3044168A1 - GENERATOR BASED ON SOLID PIEZOELECTRIC MATERIAL IN SOFT STRUCTURE - Google Patents

Abstract

Electric generator comprising a superposition including two electrode layers (1, 3), a layer of piezoelectric material (2) with a thickness between 10 and 60 microns interposed between the two electrode layers (1, 3) and a layer substrate (4) supporting one of the electrode layers (1).

Description

The invention relates to the field of flexible and flexible piezoelectric structures, in particular generators and electronic assemblies comprising such generators.

Massive piezoelectric materials are among the most efficient solutions for energy generation. This energy generation can be done by pressing or bending the material.

In the case of pressure, the thicker the piezoelectric material, the more energy will be produced. Nevertheless, the pressure that it is necessary to apply increases with the thickness, which limits are use.

In the case of bending, the energy generation increases with the amplitude of the flexion, the arrow. Nevertheless, the piezoelectric materials which are in the form of single crystals or ceramics exhibit great fragility. This fragile nature of ceramics and single crystals drastically limits the service life and the conditions of use in flexion.

It is known to provide thin layers of piezoelectric materials, less than a few micrometers thick. Such layers are for example described in US2012 / 0312456. The very thin thicknesses allow a flexibility that allows a generation of energy. The processes implemented involve the use of clean room type facilities as used in the field of semiconductors. Such installations are very expensive, especially in an industrial manufacturing context. This entails unacceptable costs for applications requiring mass production.

Moreover, the deposition of thin layers also induces a completely disorganized crystalline structure of the material obtained. Since the efficiency of piezoelectric materials strongly depends on their crystalline structures, the actual piezoelectric properties of the materials obtained are considerably reduced compared to the theoretical properties based on crystal structures. The invention improves the situation.

The Applicant proposes an electrical generator comprising a superposition including: a first electrode layer; a second electrode layer; a layer of piezoelectric material having a thickness of between 10 and 60 microns interposed between the first electrode layer and the second electrode layer; and a substrate layer supporting the first electrode layer or the second electrode layer.

Such a generator supports high amplitude flexures while exhibiting intrinsic piezoelectric properties close to the theoretical properties. Mechanical energy can be converted into electrical energy with improved efficiency. The breaking strength and the service life of such generators are improved.

The generator may have the following optional characteristics, alone or in combination with each other: the thicknesses of the first electrode layer, the second electrode layer, the piezoelectric material layer and the substrate layer as well as their respective compositions are jointly selected so that a superposition having a length of five centimeters can be reversibly bent until the tangents at the ends form between them an angle greater than 10. This allows the use of the generator in many applications and in particular those for which large amplitude movements are present and whose mechanical energy can supply the generator. the layer of piezoelectric material comprises at least one of the following materials: a titanium lead zirconate (PZT) ceramic, monocrystals of: lead niobate magnesium titanate (Pb (Mgi / 3Nb 2/3) ox) Tix03 ; PMN-PT), - quartz (S1O2), - zinc oxide (ZnO), - barium titanate (BaTiCE), - strontium / barium niobate (SrxBa (ix) Nb2C> 6, SBN), - tantalate-niobate potassium (KTao-x) NbxO3; KTN), - lead niobate zinc titanate (Pb (ZnI / 3Nb2 / 3) o-x) TixO3; PZN-PT), and lithium niobate (LiNbCb). Such materials have particularly effective piezoelectric properties. the layer of piezoelectric material has a thickness of between 20 and 40 microns. Such a thickness gives the superposition a large deformation capacity, especially in bending while allowing sufficient energy efficiency for the power supply of a battery. at least one of the first electrode layer and the second electrode layer comprises copper, chromium, titanium, aluminum and / or gold (Au). These materials can be easily deposited by techniques known per se. at least one of the first electrode layer and the second electrode layer has a thickness of between 0.1 and 0.6 micrometers. Such thicknesses allow large deformations while having a low risk of occurrence of deterioration and electrical defects due to numerous flexions. the substrate layer is based on at least one of poly (4,4'-oxydiphenylenepyromellitimide) (Kapton), polyethylene terephthalate (PET), polyvinylidene fluoride; ) (PVDF) and a rolled metal sheet. Such materials are particularly suitable for undergoing many deformations with good fatigue behavior. the substrate layer has a thickness of between 13 and 65 microns. Such a thickness gives the superposition a large capacity for deformation, especially in flexion while sustainably supporting the other layers of the superposition. the layer of piezoelectric material has a piezoelectric coefficient greater than 100 pm / V. Such a coefficient makes the generator suitable for power supply applications and not only for sensor functions.

According to a second aspect of the invention, the Applicant proposes an electronic assembly comprising a generator as defined above coupled to an accumulator so that a bending of the superposition of the generator generates a storage of energy by the accumulator.

The substrate layer of the generator can support at least part of the accumulator. Such an assembly is particularly compact. It can be integrated into many devices whose energy autonomy is sought.

The generator of the assembly may be connected to a microcontroller arranged to draw pressure information and / or deformation of the superposition of the generator from a signal output of the generator. The assembly can then form both a sensor and a power source. The electronic assembly may further comprise a transmitter arranged to transmit information derived from a signal at the output of the generator. Many devices can be made energetically autonomous and / or communicating.

According to a second aspect of the invention, the Applicant proposes a method of manufacturing a generator comprising the following steps: a) depositing on a solid layer of piezoelectric material a layer of conductive material so as to form a first electrode layer , b) fixing the superposition obtained in a) on a first working support, c) thinning the solid layer of piezoelectric material to obtain a solid layer of thinned piezoelectric material with a thickness of between 10 and 60 micrometers, d) depositing on the solid layer of thinned piezoelectric material of the superposition obtained in c) a layer of conductive material, e) fixing a substrate layer on a second working support, f) depositing on the substrate layer the superposition obtained in e) a layer of conductive material, g) apply the conductive material layers deposited respectively in d) and f) one against the and pressing the overlays obtained respectively in d) and f) to obtain a molecular bond between said layers of conductive material to form a single second electrode layer, and h) removing the first and second work media .

The layer of conductive material deposited in a) and / or the two layers of conductive material deposited in d) and f) may have a plurality of electrically insulated areas from each other so as to obtain coplanar contact pads. Connection with other components is facilitated.

The steps a) to d) can be carried out twice so as to obtain two distinct overlays, the steps e) to h) are performed twice successively on one side of the substrate layer and then on the opposite face, respectively with the one then the other of said two distinct overlays. The superposition has an efficiency doubled for a small footprint and a less expensive manufacture than to perform two overlays. Other features, details and advantages of the invention will appear on reading the following detailed description, and the attached drawings, in which: FIG. 1 shows a perspective view of a generator according to the invention; FIG. 2 shows a sectional view of a detail of the generator of FIG. 1; FIGS. 3A to 3H show steps of a method of manufacturing a generator according to the invention; FIGS. each show an embodiment of a generator according to the invention, - Figure 8 shows a schematic diagram of a signal output of the generator according to the deformations applied to it, - Figure 9 shows an electronic assembly according to the invention equipped with a generator according to the invention, - Figure 10 is a graph showing a signal at the output of the assembly of Figure 9 according to the deformations that are applied to the generator, and - the Figures 11 and 12 each show an embodiment of an assembly according to the invention.

The drawings and the description below contain, for the most part, elements of a certain character. They can therefore not only serve to better understand the present invention, but also contribute to its definition, if any.

In the field of piezoelectric, the term "thin (s)" generally refers to layers or structures of thickness ranging from a few hundred nanometers to a few micrometers, about 3 microns. The term "solid (s)" refers to the contrary layers or structures of thickness at least equal to ten micrometers and up to several hundred micrometers. In the following, these definitions are respected.

Reference is made to FIGS. 1 and 2 which show an electric generator in the form of a superposition of several layers. The superposition comprises: a first electrode layer 1; a layer of piezoelectric material 2; a second electrode layer 3; and a substrate layer 4.

The first electrode layer 1 and the second electrode layer 3 each have a thickness of between 0.1 and 0.6 micrometers. Here, the first electrode layer 1 has a thickness of about 0.2 micrometer (2000 Å) while the second electrode layer 3 has a thickness of about 0.4 micrometer (4000 Å). In the example described here, the first electrode layer 1 and the second electrode layer 3 comprise conductive components, alone or in superposed layers, for example copper (Cu), chromium (Cr), titanium ( Ti), aluminum (Al) and / or gold (Au).

The layer of piezoelectric material 2 has a thickness of between 10 and 60 microns, preferably between 20 and 40 microns. In the example described here, the thickness is about 30 microns. The layer of piezoelectric material 2 of the generator thus forms a massive structure.

The layer of piezoelectric material 2 comprises at least one of: - a titanium lead zirconate (PZT) ceramic, - monocrystals of: - lead niobate magnesium titanate (Pb (Mgi / 3Nb2 / 3) (ix) TixC> 3; PMN-PT), - quartz (S1O2), - zinc oxide (ZnO), - barium titanate (BaTiCb), - strontium / barium niobate (SrxBa (iX) Nb206, SBN), - tantalate- potassium niobate (KTa (iX) Nbx03; KTN), - lead zinc niobate titanate (Pb (Zni / 3Nb2 / 3) (ix) TixO3; PZN-PT), and lithium niobate (LiNbCb).

In the example described here, the layer of piezoelectric material 2 is made of PZT ceramic.

The layer of piezoelectric material 2 is sandwiched between the two electrode layers 1 and 3.

The substrate layer 4 supports the superposition of the other three layers. It is here disposed under the second electrode layer 3. The substrate layer 4 has a thickness of between 13 and 65 microns, here about 30 microns. The substrate layer 4 has a structure and a composition arranged to give it great flexibility and facilitate the flexibility of the superposition. It can be electrically conductive or insulating. For example, the substrate layer 4 may be made from a laminated metal sheet. The substrate layer 4 can also be made based on polymers such as poly (4,4'-oxydiphenylene-pyromellitimide), also known under the trade name "Kapton", poly (ethylene terephthalate) or PET, poly (vinylidene fluoride) or PVDF). The substrate layer 4 may also have an assembly of several materials, for example in the form of a multilayer.

The substrate layer 4 may alternatively have one or two of its main faces covered with conductive metal, for example copper. Such coatings may, for example, facilitate adhesion with the electrode layer of the superposition, in particular as a function of the materials used.

The superposition of the four layers has a total thickness of between about 23 and 125 micrometers.

In the example of Figure 1, the first electrode layer 1 is full on its entire surface. In other words, it has a single zone. Alternatively, the first electrode layer, forming the upper electrode in the figures, may have different organizations and include a plurality of areas electrically insulated from each other so as to form coplanar contact pads. Examples of such organizations are shown in Figures 4, 5 and 7. The areas of the first electrode layer 1 are then referenced IA, IB, IC, etc. Similarly, the second electrode layer 3 may also have areas electrically insulated from each other. Such areas are shown in Figures 1, 4, 5, 6 and 8. These areas are referenced 3A, 3B, 3C, etc. Alternatively, the second electrode layer 3 may be full.

In operation, a zone of the first electrode layer 1 and a zone of the second electrode 3 facing each other on either side of the layer of piezoelectric material 2 form a pair. Each pair is associated with a position in the main plane of the generator. It is then possible to associate an electrical measurement or a power generation at a location of the generator in its main plane. Depending on the intended applications, the zone configuration is adapted. This type of organization is particularly suitable for deformation sensor applications.

To do this, each pair is electrically connected to a circuit and separate components of the generator.

As shown in the figures, the first electrode layer 1 here has a free face. Connecting it electrically to external components does not pose any particular difficulty. On the contrary, the second electrode layer 3 is trapped between the layer of piezoelectric material 2 and the substrate layer 4. To facilitate the connections with external circuitry, a small branch portion of one face of the second electrode layer 3 is left free, not covered by the layer of piezoelectric material 2, and forms a connection pad so that the second electrode layer 3 can easily be electrically connected to other components. The second electrode layer 3 being formed of a single zone, it then forms the mass common to each of the pairs distributed in the main plane of the generator. The portion left free form then plot-mass. The ground stud is referenced 3B in FIG. 1, 3D in FIG. 4, 3J in FIG. 53B in FIG. 6. Other pads isolated from one another and isolated from the second electrode layer 3 are arranged adjacent to the grounding pad. These pads are, here, at least as many as the number of zones provided in the first electrode layer 1. Each of these pads then forms a connection intermediate for a respective zone of the first electrode layer. For example, in FIG. 4, the pad referenced 3A is electrically connected to the area IA, the pad referenced 3B is electrically connected to the area IB, the pad referenced 3C is electrically connected to the area IC. These links may, for example, be made using a conductive wire. Thus, when the generator 1 is integrated in an electronic assembly, the studs, whose stud-mass are locally grouped, which facilitates connections and reduce clutter.

Reference is now made to FIGS. 3A to 3H showing steps for manufacturing a generator, for example one of those described above.

In a first step a), the result of which is represented in FIG. 3A, a piezoelectric solid material 201 is covered with an electrode layer 101 on one of its main faces. The piezoelectric solid material 201 has an initial thickness greater than 500 microns. At the end of the process, the electrode layer 101 will form the first electrode layer 1 as described above. The electrode layer 101 here has a thickness of about 0.2 micrometer (2000 Å). The metal deposition can be carried out under vacuum by physical vapor deposition (PVD) or plasma enhanced chemical vapor deposition (PECVD).

In a second step b), the result of which is represented in FIG. 3B, the superposition 101, 201 obtained in step a) is fixed on a first working support 601. The free face of the electrode layer 101 is applied against the first work support 601 while the opposite face of the piezoelectric solid material 201 is left free. The first work support 601 has, here, a thickness greater than 2 millimeters. In the example described here, it takes the form of a glass slide. In general, the first work support 601 is arranged to facilitate the manipulation of the superposition during the subsequent steps. Fixing studs 501 maintain the superposition 101, 201 on the first working support 601. The fixing studs 501 are arranged so as not to interfere with the following process steps.

In a third step c), the result of which is represented in FIG. 3C, the piezoelectric solid material 201 is thinned from its free face. This thinning is here achieved by a traditional lapping / polishing operation. This results in a layer of thinned piezoelectric material 202. Although thinned with respect to the initial piezoelectric solid material 201, the thinned piezoelectric material layer 202 remains solid. The thickness of the latter is adapted according to the intended application. Here, it is thinned to about 30 microns. During this step, the electrode layer 101 remains unchanged under the layer of thinned piezoelectric material 202.

In a fourth step d), the result of which is shown in FIG. 3D, the face of the thinned piezoelectric material layer 202 opposite to that carrying the electrode layer 101 is in turn covered by an electrode layer 301, that is to say on the side which has undergone thinning in step c). At the end of the process, the electrode layer 301 will form a part of the second electrode layer 3 as described above. The electrode layer 301 here has a thickness of about 0.2 micrometer (2000 Å). The metal deposition can be carried out under vacuum by physical vapor deposition (PVD) or plasma enhanced chemical vapor deposition (PECVD).

The superposition obtained at the end of step d) is retained for use in step g) described below.

In a fifth step e), the result of which is represented in FIG. 3E, a substrate layer 4 is fixed on a second working support 602. The second working support 602 is, here, similar to the first working support 601. fixing lips 7 hold the substrate layer 4 on the second working support 602. The fixing lips 7 are arranged so as not to interfere with the following process steps.

In a sixth step f), the result of which is represented in FIG. 3F, the substrate layer 4 is covered with an electrode layer 302 on its free main face, that opposite to the second working support 602. At the end of FIG. method, the electrode layer 302 will form in combination with the electrode layer 301 the second electrode layer 3 as described above. The electrode layer 302 here has a thickness of about 0.2 micrometer (2000 Å). The metal deposition can be carried out under vacuum by physical vapor deposition (PVD) or plasma enhanced chemical vapor deposition (PECVD).

In a seventh step g) shown in FIG. 3G, the superposition obtained in step d) and that obtained in step f) are assembled with each other, here by cold pressing ("cold welding" in English). The two electrode layers 301 and 302 are applied against each other. The two overlays are pressed against each other until a molecular bond is obtained between the two electrode layers 301 and 302. The pressing conditions are adapted according to the materials used. They then merge with each other so that the two overlays are attached to each other and a single second electrode layer 3 is formed. The thickness of the second electrode layer 3 then substantially corresponds to the sum of the thicknesses of the electrode layers 301 and 302, here about 0.4 micrometers (4000 Å).

In the case of separate and insulated areas on the same plane as illustrated in Figures 1, 4, 5, 6 and 7, the zones are modeled during deposition operations, prior to assembly by pressing.

In an eighth step h) represented in FIG. 3H, the superposition obtained at the end of step g) is released from the working supports 601 and 602. During the extraction of the working supports 601, 602, the physical or chemical techniques used implemented are adapted according to the materials used.

Steps a) to d) on the one hand and steps e) and 1) on the other hand can be performed independently. Alternatively, the thinning step can be performed upstream of the other steps, for example by a third party supplier, different from that implementing the other steps.

Reference is now made to FIG. 7. In this embodiment, the two faces of the substrate layer 4 comprise, prior to the implementation of the above method, zones of electrical conductivity. Steps a) to d) are performed twice so as to obtain two distinct superpositions corresponding to the product at the end of step d). Then, steps e) to h) are performed twice successively, on one side of the substrate layer 4 and then on the opposite face, respectively with one then the other of the two distinct overlays obtained at the end of the steps of FIG. ).

There is then obtained a generator as shown in FIG. 7 for which two piezoelectric layers are supported by a common substrate layer 4.

The generators as described hitherto exhibit a particularly flexible deformation behavior. The Applicant has measured the bending angle allowed on generators having a substantially rectangular shape as shown in Figure 1, and a length of about 5 centimeters. An angle of at least 10 ° or even 45 ° in absolute value can be reached while remaining in the elastic domain of the superposition. In other words, such flexion remains reversible. The intrinsic properties of the generator, in particular piezoelectric, are preserved. By bending 45 °, is meant here that the tangent at one end of the rectangular shape of the superposition forms an angle of ± 45 ° with the direction of rest of the superposition while the opposite end is blocked, as shown in Figure 8. Repeated bending at angles of ± 60 ° and even ± 90 ° could be achieved without degrading the efficiency of the generator.

Reference is now made to FIG. 8, in which curves represent the results obtained at the output of the generator as a function of the deformations undergone. On the ordinate of the graph of FIG. 8 are represented on a double scale the states of voltage and current generated during four deformation phases.

The first phase corresponds to a first bending upward with an angle of about 60 °. The changes in voltage and current are observed. The voltage reaches a maximum of +5 volts in the maximum angle position and the current reaches +9 μ A very quickly then stagnates at + 9μΑ before returning to 0, when there is no more bending movement.

The second phase corresponds to the return to the initial position, at rest. The bending is then in the other direction. The voltage returns to 0 volts with the displacement and the current changes in the same way as during the first phase with an opposite sign because it is dependent on the direction of the movement.

Phases 3 and 4 are respectively the same as phases 1 and 2, but bending movements are operated in the opposite direction. The same behaviors in tension and current are observed but with opposite signs.

Reference is now made to FIG. 9, which schematically represents an electronic assembly intended to cooperate with a generator as described above. The assembly comprises an electronic circuit including at least one electronic voltage rectifier 5, a processing subset 6 including at least one microcontroller for the processing and management of output voltages and currents, a battery / storage capacity 7 of energy, an output connector + Vs and a ground connector. In the example described here, the zone 3A of the generator of FIG. 1 is connected to the + Vin input of the assembly of FIG. 9 while the zone 3B of the generator of FIG. 1 is connected to the input. -Vin of the whole of Figure 9. The mechanical energy of the bending of the generator is converted into electrical energy by direct piezoelectric effect and stored in the battery / capacity 7. The stored energy is restored through the output connector + Vs and mass to an electronic device not shown here.

FIG. 11 is a diagram showing an assembly including a generator similar to that of FIG. 1 and in which the substrate layer 4 further receives a rectifier bridge 5. The rectifier bridge 5 is here of CMS type and is directly fixed on the substrate 4. The rectifier bridge 5 is inserted between the zones 3A and 3B of the generator and two output connectors 3AR and 3BR. Figure 10 illustrates the rectified voltages and currents obtained at the output connectors 3AR and 3BR. The output currents and voltages are all of positive sign, regardless of the direction of the deformation of the generator 1. The outputs 3AR and 3BR can therefore directly supply energy storage members such as batteries. The outputs 3AR and 3BR can be connected to an electronic device not shown to supply power and / or provide a signal representative of the deformation of the superposition. The generator forms in this case a deformation sensor.

Figure 12 shows an assembly for which a subset corresponding to the assembly of Figure 9 is integrally attached to the substrate layer 4 of a generator. The operation is substantially similar but has a particularly limited footprint that promotes implementations in lightweight objects, such as clothing.

Generators and assemblies equipped with such generators have a general structure that is flexible, flexible and lightweight. They implement the direct piezoelectric effect with an efficiency close to the theoretical possibilities of massive piezoelectric structures, a much higher efficiency than that of thin films. By way of comparison, the coefficient D33 of a solid piezoelectric material generally has a value of approximately 400 pm / V. The same thin-film material generally has a coefficient of about 20 pm / V, which is twenty times lower. The Applicant has observed on the generators as described here piezoelectric coefficients greater than 100 pm / V (or 100 pC / N), significantly higher than those of thin layers, comparable to those of non-flexible bulk materials.

In association with a communication device, for example of the USB, Wifi, Bluetooth, RFID or Infrared type, such generators make it possible to communicate a large number of electronic devices without this adversely affecting energy autonomy. The increase in the power consumption induced by the communication devices being at least partly compensated by the energy produced by the generator from mechanical energy already available but usually not used.

The generators can act as a pressure sensor and / or deformation totally or partially autonomously energy, and optionally communicating.

The generators are particularly suitable for portable or implantable energy harvesting devices, such as generators housed in shoe soles, or implantable devices that harvest energy from the respiratory movements of users.

Portable or ambulatory devices, generally called "wearables", can become energetically autonomous or almost. The operation of recharging a battery by a connection to an external source such as the sector becomes useless or very rare.

The generators are suitable for human movements such as walking and running. They can be easily integrated into clothes. They respect the criteria generally accepted as necessary for this type of application, including lightness, miniaturization, flexibility, robustness and manufacturing costs.

The structure of the generator and its method of manufacture described here make it possible to exploit a massive structure of piezoelectric material - whose intrinsic properties are much higher than those of thin layers - in a flexible operating mode adapted to the movements of the human being.

The structure of the generator is made of massive materials whose intrinsic properties are preserved during the manufacturing process. The proposed solution constitutes an efficient means supporting the use of ceramic materials or piezoelectric single crystals in the bending regime, while offering great performance in energy generation thanks to the preserved massive piezoelectric properties. The invention is not limited to the examples of generators and assemblies described above, only by way of example, but it encompasses all the variants that can be considered by those skilled in the art in the context of the claims below. after.

Claims (16)

claims An electric generator comprising a superposition including: a first electrode layer (1); a second electrode layer (3); a layer of piezoelectric material (2) with a thickness of between 10 and 60 microns interposed between the first electrode layer (1) and the second electrode layer (3); and - a substrate layer (4) supporting the first electrode layer (1) or the second electrode layer (3). 2. Generator (1) according to claim 1, wherein the thicknesses of the first electrode layer (1), the second electrode layer (3), the layer of piezoelectric material (2) and the layer substrate (4) and their respective compositions are jointly selected so that a superposition having a length of five centimeters can be reversibly curved until the tangents at the ends form an angle greater than 10 ° between them. 3. Generator (1) according to one of the preceding claims, wherein the layer of piezoelectric material (2) comprises at least one of the following materials: - a titanium lead zirconate (PZT) ceramic, - single crystals of: - titanate niobate lead magnesium (Pb (Mgi / 3Nb2 / 3) (ix) Tix03; PMN-PT), - quartz (S1O2), - zinc oxide (ZnO), - barium titanate (BaTiCb), - niobate strontium / barium (SrxBa (iX) Nb206; SBN), - potassium tantalate-niobate (KTa (iX) Nbx03, KTN), - lead niobate zinc titanate (Pb (Zni / 3Nb2 / 3) (iX) TixC> 3 PZN-PT), and lithium niobate (LiNbCb). 4. Generator (1) according to one of the preceding claims, wherein the layer of piezoelectric material (2) has a thickness between 20 and 40 microns. 5. Generator (1) according to one of the preceding claims, wherein at least one of the first electrode layer (1) and the second electrode layer (3) comprises copper (Cu), chromium (Cr), titanium (Ti), aluminum (Al) and / or gold (Au). 6. Generator (1) according to one of the preceding claims, wherein at least one of the first electrode layer (1) and the second electrode layer (3) has a thickness between 0.1 and 0.6 microns. 7. Generator (1) according to one of the preceding claims, wherein the substrate layer (4) is made based on at least one of poly (4,4'-oxydiphenylene-pyromellitimide) (Kapton), poly (ethylene terephthalate) (PET), polyvinylidene fluoride (PVDF) and a rolled metal sheet. 8. Generator (1) according to one of the preceding claims, wherein the substrate layer (4) has a thickness between 13 and 65 micrometers. 9. Generator (1) according to one of the preceding claims, wherein the layer of piezoelectric material (2) has a piezoelectric coefficient greater than 100 pm / V. 10. Electronic assembly comprising a generator (1) according to one of the preceding claims coupled to an accumulator so that a bending of the superposition of the generator (1) generates energy storage by the accumulator. 11. The assembly of claim 10, wherein the substrate layer (4) of the generator (1) at least partially supports the accumulator. 12. Electronic assembly comprising a generator (1) according to one of claims 1 to 9 connected to a microcontroller arranged to pull pressure information and / or deformation of the superposition of the generator (1) from a signal in generator output (1). 13. Electronic assembly according to one of claims 10 to 12 further comprising a transmitter arranged to transmit information from a signal output of the generator (1). A method of manufacturing a generator (1) comprising the following steps: a) depositing on a solid layer of piezoelectric material (201) a layer of conductive material (101) so as to form a first electrode layer (1). ), b) fixing the superposition obtained in a) on a first working support (601), c) thinning the solid layer of piezoelectric material until a solid layer of thinned piezoelectric material (202) with a thickness of 10 and 60 micrometers, d) depositing on the solid layer of thinned piezoelectric material (202) the superposition obtained in c) a layer of conductive material (301), e) attaching a substrate layer (4) on a second work support (602), f) depositing on the substrate layer (4) the superposition obtained in e) a layer of conductive material (302), g) applying the layers of conductive material (301, 302) deposited respectively in d) and in f) one of them contrasting each other and pressing the overlays obtained respectively in d) and f) to obtain a molecular bond between said conductive material layers (301, 302) so as to form a single second electrode layer (3), and h) removing the first and second work supports (601, 602). 15. The method of claim 14 wherein the layer of conductive material (101) deposited in a) and / or the two layers of conductive material (301, 302) deposited in d) and 1) have a plurality of electrically insulated areas. each other so as to obtain coplanar contact pads (1A, 1B, 1C, 3A, 3B, 3C). 16. Method according to one of claims 14 and 15 wherein the steps a) to d) are performed twice so as to obtain two distinct overlays, the steps e) to h) are performed twice successively on one side of the substrate layer (4) then on the opposite face, respectively with one then the other of said two distinct overlays.